[all-commits] [llvm/llvm-project] a54d02: Revert "[libc++] Remove extension to support alloc...

[Louis Dionne via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: a54d028895c91da356a4aaf30e27a5a5b90dd313
      https://github.com/llvm/llvm-project/commit/a54d028895c91da356a4aaf30e27a5a5b90dd313
  Author: Louis Dionne <ldionne.2 at gmail.com>
  Date:   2022-03-09 (Wed, 09 Mar 2022)

  Changed paths:
    M libcxx/docs/ReleaseNotes.rst
    M libcxx/include/__memory/allocator.h
    M libcxx/include/__memory/shared_ptr.h
    M libcxx/include/memory
    A libcxx/test/libcxx/containers/sequences/vector/const_value_type.pass.cpp
    R libcxx/test/libcxx/memory/allocator.cv.verify.cpp
    M libcxx/test/libcxx/memory/allocator_void.trivial.compile.pass.cpp
    A libcxx/test/libcxx/memory/allocator_volatile.verify.cpp
    M libcxx/test/std/concepts/concepts.lang/concept.default.init/default_initializable.compile.pass.cpp
    M libcxx/test/std/utilities/memory/default.allocator/allocator.ctor.pass.cpp
    M libcxx/test/std/utilities/memory/default.allocator/allocator.dtor.pass.cpp
    M libcxx/test/std/utilities/memory/default.allocator/allocator.members/allocate.constexpr.size.verify.cpp
    M libcxx/test/std/utilities/memory/default.allocator/allocator.members/allocate.size.pass.cpp
    M libcxx/test/std/utilities/memory/default.allocator/allocator_types.deprecated_in_cxx17.verify.cpp
    M libcxx/test/std/utilities/memory/default.allocator/allocator_types.pass.cpp
    M libcxx/test/std/utilities/memory/default.allocator/allocator_types.removed_in_cxx20.verify.cpp
    M libcxx/test/std/utilities/memory/specialized.algorithms/specialized.construct/construct_at.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/auto_ptr.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/deduction.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/default.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/nullptr_t.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/nullptr_t_deleter.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/nullptr_t_deleter_allocator.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/pointer.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/pointer_deleter.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/pointer_deleter_allocator.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/shared_ptr.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/shared_ptr_Y.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/shared_ptr_Y_rv.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/shared_ptr_pointer.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/shared_ptr_rv.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/unique_ptr.pass.cpp
    M libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/weak_ptr.pass.cpp

  Log Message:
  -----------
  Revert "[libc++] Remove extension to support allocator<const T>"

This reverts commit 276ca873. That commit has quite a history at this
point. It was first landed in dbc647643577, which broke std::shared_ptr<T const>
and was reverted in 9138666f5. It was then re-applied in 276ca873, with
the std::shared_ptr issue fixed, but it caused widespread breakage at
Google (which suggests it would cause similar breakage in the wild too),
so now I'm reverting again.

Instead, I will add a escape hatch that vendors can turn on to enable
the extension and perform a phased transition over one or two releases
like we sometimes do when things become non-trivial.